AP PHOTO
Celtics head coach Doc Rivers gives forward Kevin Garnett a pat on the back after taking him out of the game in the final minute of Game 6 against the New York Knicks on Friday night in Boston.

BOSTON — This offseason will be a lot like the last one for the Boston Celtics.

Except they’re another year older.

Kevin Garnett and Paul Pierce could be heading for retirement, or they could be trade bait to kickstart a rebuilding effort. Coach Doc Rivers also wouldn’t commit to another season with the Celtics after they were eliminated from the playoffs Friday night with an 88-80 loss to the New York Knicks in Game 6 of their first-round series.

“Honestly, I just can’t even think about that right now. So I don’t know,” said Rivers, who is under contract for another three years. “If I told you right now, I’m coming back. But like I just said, I immerse myself (in the season) and I need to just detox, and we’ll find that out.”

Pierce will be 36 when next season starts. He is under contract for one more year, but he has already been through one rebuilding period with the team and might not want to stick around for another that wouldn’t pay off until he is too old to participate.

The longest-tenured Celtics player, Pierce averaged 18.6 points, 6.3 rebounds and 4.8 assists this season. He scored 19.2 points per game in the Knicks series, but he shot just 37 percent from the field and 27 percent from 3-point range.

“He’s one of the greatest Celtics to ever play. He’s done so much for this franchise,” Rivers said. “Listen, we live in a day and time where guys are changing teams like socks. And Paul has chosen to stay here throughout his career, when clearly he had all rights to leave.

“I have so much respect for him, for that. ... Paul, he never wavered. So I give him that, and just an amazing amount of respect. He wanted to get it done here; he made that choice. Where other guys are running around trying to find it, Paul decided, `I’m going to stay here, and see if we can win it.’ And he did that. So I hope he’s remembered for that, and obviously I hope he comes back.”

Pierce said it will be up to general manager Danny Ainge to decide whether to take apart the core of the team that won the franchise’s record 17th NBA title in 2008 and returned to the finals two years later. Ray Allen left as a free agent last summer, leaving only Garnett, Pierce and point guard Rajon Rondo from the championship team.

Despite Boston’s comeback from a 3-0 hole in the best-of-seven series and a 20-0 run that nearly eliminated a 26-point deficit in Game 6, Rivers conceded that the Knicks were the better team. The Celtics need to add something, he said, and the question is whether to trade away one of the stars to get it.

“We need more,” Rivers said repeatedly. “But the key is, for us, do you want to take away to get more? And that will be a decision that will be made later.”

Rondo was done for the season after tearing a ligament in his right knee in late January. First-round draft pick Jared Sullinger needed back surgery less than a week later. Guard Avery Bradley, one of the team’s top defenders, missed the first half of the season with injuries to both shoulders and could join Rondo to make a formidable backcourt that would be the centerpiece of a rebuilding effort.

Pierce said he didn’t know whether he would be part of it.

“You know, that’s hard to say,” he said. “I think that’s a question for Danny Ainge and his team to figure out, so I have no idea.”

Garnett, who turns 37 next month, doesn’t have the longevity in Boston that Pierce does. But he said he is tied to his teammate.

“One of the big reasons I came here was because of Paul,” Garnett said. “Obviously, you want to be in a situation where it’s better. I want to make sure I can always help the team, want to be in position to where I’m giving something.

“I demand a lot out of myself, both physically and from a skill level,” Garnett said. “I’ll be honest, or I’ll be lying to you if I said Paul didn’t play into that.”